1. Field
One or more exemplary embodiments relate to a golf ball, and more particularly, to a golf ball having divided spherical surfaces in order to effectively arrange dimples thereon.
2. Description of the Related Art
In order to arrange dimples on a surface of a golf ball, the surface of a sphere is generally divided by the great circles into a spherical polyhedron having a plurality of spherical polygons. A great circle is formed by an intersection of the surface of the sphere with a plane passing through a central point of the sphere. A small circle is a circle drawn on the surface of the sphere, other than the great circle.
The dimples are arranged on the spherical polyhedron in such a manner that the dimples have spherical symmetry. Most spherical polyhedrons that are frequently used to arrange dimples of a golf ball include spherical regular polygons. Examples of the spherical regular polyhedrons may be a spherical tetrahedron having four spherical regular triangles, a spherical hexahedron having six spherical squares, a spherical octahedron having eight spherical regular triangles, a spherical dodecahedron having twelve regular pentagons, a spherical icosahedron having twenty spherical regular triangles, a spherical cubeoctahedron having six spherical squares and eight spherical regular triangles, an icosidodecahedron having twenty spherical regular triangles and twelve spherical regular pentagons, or the like.
On existing golf balls, three to four hundred dimples are symmetrically arranged on a spherical polyhedron having spherical polygons formed by dividing the surface of the sphere by the great circles only. When a mold cavity is manufactured with two to four types of diameters of the dimples, the land surfaces on which the dimples are not arranged increases. When the area of the land surface becomes relatively larger, a lift force regarding flight of the golf ball is affected, and thus, a flight distance of the golf ball is reduced. Therefore, in order to solve such a problem, various types of dimples having very small diameters are arranged on a golf ball to reduce the area of the land surface as small as possible.
U.S. Pat. No. 4,560,168 discloses an example of the surface of a golf ball which is divided by the great circles. On the golf ball, each of the triangles of a regular icosahedron is divided into four triangles by six great circles, to thus form twenty small triangles and twelve pentagons, that is, a spherical icosidodecahedron, where the dimples are arranged.
However, conventionally, more types of dimples are needed overall. Accordingly, it's costing too much to make a mold cavity. Also, the appearance of the golf ball is aesthetically poor.
Furthermore, in the case of a spherical polyhedron including at least two types of spherical regular polygons, the diameters of dimples vary with the types of the spherical regular polygon, which make a difference in the air flow, and thus the flight performance of the golf ball may be changed.
FIGS. 5 and 6 show a golf ball 200 of the related art. The golf ball 200 has a spherical truncated icosahedral surface obtained by dividing a spherical icosahedron by the great circles. The spherical truncated icosahedron may be obtained by dividing a surface of a sphere by the great circles into a spherical icosahedron including spherical regular triangles and then cutting off vertex portions of each spherical regular triangle, and the spherical truncated icosahedron includes twelve spherical regular pentagons and twenty spherical regular hexagons. The spherical truncated icosahedron is well known as a spherical polyhedron that has been mainly used to produce a soccer ball, but the spherical truncated icosahedron has also been used as a surface segmental structure that is adapted to arrange the dimples of a golf ball. However, when the dimples having the sizes greater than a certain size are arranged on the surface of the golf ball which divided into the spherical truncated icosahedrons, the land surfaces on which the dimples are not arranged is considerably formed.